; -*- Mode: Scheme; Syntax: Scheme; Package: Scheme; -*-

; This is file bare.scm.

;;;; "Bare machine"

; Random things needed to build the datatypes and GC.

; error

(define unassigned
  (let ((marker (list '<unassigned>)))
    (lambda () marker)))

(define (assert test)
  (if (not test) (error "assertion failed")))

; I/O

;(define peek-char --undefinable--)

; Strings, vectors

(define %make-string make-string)  ;Used by extract-string
(define %string-set! string-set!)
(define %make-vector make-vector)  ;Used by i/o system
(define %vector-ref  vector-ref)
(define %vector-set! vector-set!)
(define %vector-length vector-length)
(define %vector-posq vector-posq)

; 28-bits integer operations

(define +&  +)
(define -&  -)
(define *&  *)
(define =&  =)
(define <&  <)
(define <=& <=)
(define >&  >)
(define >=& >=)
(define quotient&  quotient)
(define remainder& remainder)

(define (adjoin-bits high low k)
  (+ (* high (expt 2 k)) low))

(define (low-bits n k)
  (modulo n (expt 2 k)))

(define (high-bits n k)
  (let ((two^k (expt 2 k)))
    (if (>= n 0)
	(quotient n two^k)
	(quotient (- n (- two^k 1)) two^k))))

(define (logand x y)
  ;; Assumes that y is one less than a power of two,
  ;; since that's the only case used by S48.  Whatta kludge!
  (modulo x (+ y 1)))